Handle missing default phone

If default phones have not been created, make the receiver a no-op.

Test: atest SafetySourceReceiverTest
Bug: 325460602
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:553d5dbd17df6ae96f878c71e9bd4fe593a47b44)
Merged-In: Ic2108ccd3025a0986fa5b12067ad1906faa14193
Change-Id: Ic2108ccd3025a0986fa5b12067ad1906faa14193
1 file changed